Step-cutting device



Kc. H. MAnsEN. -slTEP cume DEVICE. APPLICATION flLED OCT. 20, 1919.

Patented Jima A13, 1922.

oFFIE-f CHARLES H. MADSEN, 0F TROY, NEW YORK. Y

swr-CUTTING innvion v iaiasss.

Specification of Letters Patent. Patented June 13, 1922l Application filed October 20, 1919.k Serial No. 332,087;

(FILED UNDER THE ACT 0F MARCH 3, 1883, 22 STAT. L., 625.)y i

To all whom t may concern.'

The invention described herein may be used by the Government, or any of its oflicers or employees inprosecution of work for the Government, or by any other person in the United States, without payment of any royalty thereon. y

One obj ect of this invention vis to simplify the ycustomary constructions of step-cutting devices for cutting step threads on breech blocks and in breech ends of guns.

Another object is to provide a practically non-chattering and substantially shockless device of this nature, which is a marked improvement over the customary constructions, which are characterized by shock and chatter in the operation thereof.

Another object is to provide a device, of the character indicated, which is positive, reliable and etlicient in operation,

l/Vith these objects in view, the invention resides, generally stated, in a cam-controlled cutting-tool holder maintained in constant contact with the cam by a spring, tensioned by a revolving eccentric on the same shaft as the revolving` cam, the throw of the eccentric and cam being on the saine side, insuring an equal tension on the springl at the different steps in the revolution of the cam.

The invention resides, further, in mounting the cam in a stationary housing, as distinguished from well known constructions, in which the whole housing is operated by a large cam, resulting in shock and chatter, which leaves the work in a condition necessitating considerable fitting and ling.

The accompanying drawings disclose an exemplary form of embodiment of the underlying principles of the invention, and like reference characters identify corresponding parts throughout the several views. Briefly described Figure 1 is a top plan view, partly in section, of my step-threading device, shown in operative position in relation to the work;

Figure 2 is a view in side elevation thereof;

Figure 3 is an endview thereof, looking at theend carrying the gear train; and

Figure t is a section on the line 4, 4t, Figure 1.

.Referring, now, in detail to the draw? l designates a housing suitably mounted and fastened on the cross slide of a lathe, and carrying a lateral extension 2.v

Laterally carried by the extension 2 is a casing 3, which is hollow to provide a chamber 4 for the reception of a slidable toolholder 5, a cam 6, and an eccentric. 7.

-The cam and the eccentric are mounted on a rotatable shaft 8 extending transversely through the casing and longitudinally lthrough the extension 2 and provided, at one end thereof, with a gear 9, which is one gear, of a train comprising gears 9, 10, 11 and 12, the latter being carried by a rotatable shaft 13 revoluble from a suitable source of power.

The invention compreliends suitable means for maintaining the Atool-holder 5 in :constant contact with the cam 6. The drawingdiscloses a very simple `and efcient form of such means. The exemplary form shown comprises theeccentric?, encircled by an eccentric strap 141 carrying ears 15, 15 between vwhichv is disposed, on a transverse pin 17 carried by said ears, the upper end of a rod 16. The rod passes through the upper portion of the tool-holder 5 and into a recess 18 therein. Encircling the rod 16 is a coiled spring 19 bearing, at one end thereof, against the end wall of said recess 18 and, at its other end, against a collar or nut 19 carried by the free end of said rod.

The cam 6 and eccentric 7 are, as shown in the drawing, disposed on the shaft 8 with the throw thereof on the same side, which insures an equal tension on the spring 19 at the successive steps in the revolution of the cam 6.

It will be noted that, by mounting the cam 6 in the housing 3 and providing the eccentric 7 and the spring 19 to hold the toolholder 5 firmly against the cam at all times, I have reduced shock and chatter to a negligible quantity, which is a decided advance over the prior art, so far as I am cognizant thereof, in which the whole housing is operable `by a large cam, the resulting 'chatter and shock leaving the work in a condition requiring fitting and filing.

The specific character of work being operated upon as shown in the drawing, is a breech bushing B, which is held on a chuck C by means of a threaded securing ring D and threaded bolts E passing through said ring into said chuck. j y

The operation lof the device is apparent from the above detailed description ofthe construction of the parts and their relative disposition, but, 'briefly stated, it is as follows 4When the lathe isset in motion, the cam 6 revolves, through the medium of the shaft 8 and the train of gears 9, 10, 11 and 12, moving the tool-holder 5 with the tool A against the work B, the spring 19 holding the tool-holder iirmly against the cam at all times.l Thefact that the eccentric is placed onfthe shaft 8 so its throw is on the-same side as the cam 6 insures an equal tension on the spring at the different steps of the cam.

Having described my invention, what ly claim as new and desire to secure by Letters Patent, is

1. A step threading device comprising a hollow casing, a rotatable shaft projecting therethrough, a cani carried by said shaft and disposed interiorly of the casinor a re- D7 ciprocable tool-holder projecting into said casing, and means for maintaining said toolholder in constant contact with said cam.

2. A stepthreading device comprisin a hollow casing, a rotatable shaft projecting therethrough, a cam carried bysaid shaft and disposed interiorly of the casing, a reciprocable tool-holder projecting into said casing, and means for yieldingly maintain-- ing said tool-holder in constant contact with said cam. Y

3. A step threading device comprising v-a hollow casing, a rotatable shaft projecting therethrough, a cam cairied by said shaft and disposed interiorly of the casing, a re ciprocable tool-holder projecting into said casing, and spring-actuated means for maintaining said tool-holder in constant contact with said cam.

11. A step threading device comprising a hollow casing, a rotatable shaft projecting 'i therethrough, arcam vcarried by said shaft' and disposed interiorly of the casing, a reciprocable tool-holder projecting into said casing, and means for maintaining said toolholder in constantv .contact with, said cam,

comprising an eccentric carried by said shaft and a spring operatively connected with said eccentric and said tool-holder.

5. A step threading device comprising a being disposed'on said shaft with its throw on the saine side as the cani; u,

G. A step threading device comprising a hollow casing, a rotatable sha-ft projecting therethrough, a cam ,carried by said shaft land disposed interiorly of the casinor a re-k D7 ciprocable tool-holder projecting into said casing, and means for maintaining said tool holder in constant contact withvsa'id cani comprising an `,eccentric carried byl said shaft, an eccentric strap around said eccentric`v a rod carried by said strap and projecting into said tool-holder, and a coiled spring encircling said rod and disposed in said tool-holder.

' oiiARLEs H. Mansniv. 

